Accuracy Levels of Early Cost Estimates, in Light of the Estimate Aims

摘要

This article addresses the problem of early cost estimate accuracy in the context of estimate aims. The authors list some problems caused by low accuracy. Previous work on the subject of accuracy is evaluated. The work centers around three themes: factors of the estimate methods, factors influencing cost, and the factors influencing the practice of making estimates. Many factors influencing cost are not included in the estimate methods. There are factors that are beyond the structural scope of the estimate methods. But these can influence the estimates. Most developed estimate methods only achieve an accuracy of around 16.6 percent. Estimate methods using different types of data may be used for different aims, and this may result in varying levels of accuracy. This article discusses different estimate aims, as well as the accuracy levels and kinds of data needed to reach them. The article evaluates which estimate aim is best reached by which method, and concludes with suggestions for the improvement or replacement of insufficient methods.